Before starting an Age, put the 3 King's Dice into the Tower randomly, putting each die in a different groove so as to get results in the the three specific areas. If, by mistake, you put two dice in the same groove, insert them in the Tower again. Dice indicate the buildings that you will have to include in your city during this Age.

For example, a result like this would indicate that each player needs 4 churches, two shafts, and two markets within their walls before they can "close" their city.